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Document Type

Thesis - University Access Only

Award Date

1989

Degree Name

Master of Science (MS)

Department

Wildlife and Fisheries Science

First Advisor

Lester D. Flake

Second Advisor

Charles Scalet

Abstract

The rainwater basin area in south-central Nebraska, has historically served as an important spring staging ground for migratory waterfowl. Avian cholera (Pasteurella multocida) was first reported in the rainwater basin area in 1975, and has continued to be a mortality factor each spring. Faunal, floral, physical, and water quality variables were investigated to identify possible relationships to avian cholera outbreaks in the rainwater basin area of Nebraska during 1987 and 1988. Thirty-five different aquatic invertebrate taxa were identified from 214 benthic core samples, and 26 invertebrate taxa were identified from 214 benthic core samples. Although sampling difficulties and small sample sizes precluded a complete inventory of the aquatic invertebrate species in the rainwater basin area wetlands, this study has provided base line data on the occurrence of many aquatic invertebrate species in wetlands for the region. A total of 1,715,840 live birds were counted during aerial surveys (U. S. Fish and Wildlife Service, Nebraska) on 8 study wetlands during spring of 1987, and 1,054,036 live birds were counted on 7 study wetlands during spring of 1988. The total number of dead birds picked up from study wetlands during carcass collections in 1987 and 1988 were 2,471 and 1,729, respectively. These totals include birds which died of cholera, lead poisoning, and unknown mortality factors; however, 1,256 of the dead birds collected in 1987 were diagnosed as dying of cholera. The results of this study indicated that the number of dead birds collected from study wetlands was not significantly related to the number of live waterfowl counted during aerial surveys; however, inaccuracies inherent with aerial waterfowl surveys and carcass collection methods make definitive statements pertaining to waterfowl densities versus avian cholera outbreak levels implausible. There was no apparent pattern between avian cholera outbreaks and the presence and percent coverage of emergent vegetation in the study wetlands. Dead stands of cattails (Typha glauca) were the predominant winter emergent vegetation; however, the summer vegetative mapping demonstrated that there was a considerable amount of diversity between study wetlands. Although the amount of idle land separating study wetlands from adjacent agricultural activities was variable, there was no detectable trend found between avian cholera outbreaks and adjacent land use. Water column samples were collected for chemical analyses on a weekly basis from late February through April, and on a monthly basis during May, June, and July, 198701988. Water quality differences occurred among study wetlands and between wetlands in the eastern and western regions of the rainwater basin area. Specific conductance, hardness, calcium, magnesium, sodium, chloride, and sulfate levels were generally lower in the eastern region study wetlands than in the western region study wetlands. This corroborates earlier study results of similar nature and substantiates that these chemical differences between eastern and western regions wetlands persist over time. Despite differences in water quality between studies wetlands, statistical analysis indicated that none of the water quality variables examined were found to be significantly associated with cholera outbreaks. Management recommendations include the need for a more complete inventory of aquatic invertebrates and their abundance as they relate to avian cholera outbreaks, better record keeping during carcass collections, expansion of similar studies to include the entire central flyway, and the initiation of a study to investigate the movement of waterfowl among wetlands of the rainwater basin area of Nebraska.

Library of Congress Subject Headings

Wetlands -- Nebraska
Chicken cholera
Wetland ecology
Waterfowl -- Nebraska -- Diseases

Description

Includes bibliographical references (pages 92-96)

Format

application/pdf

Number of Pages

140

Publisher

South Dakota State University

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